Amend bug 1559. standard deviation was not removed in some places.

So, sqlite crashed because std function has been removed.

git-svn-id: http://piwigo.org/svn/trunk@6125 68402e56-0260-453c-a942-63ccdbb3a9ee

include/ws_functions.inc.php

@@ -676,7 +676,6 @@ SELECT id, name, permalink, uppercats, global_rank, commentable
   $query = '
 SELECT COUNT(rate) AS count
      , ROUND(AVG(rate),2) AS average
-     , ROUND(STD(rate),2) AS stdev
   FROM '.RATE_TABLE.'
   WHERE element_id = '.$image_row['id'].'
 ;';